Makeup cosmetic compositions are generally composed of a powder component such as talc, mica, titania or coloring pigment, an oil component such as oils, fats, hydrocarbons, higher fatty acids, higher alcohols, triglycerides, ester oil or silicone oil, surfactants, polyhydric alcohols, polymers, an aqueous component, and the like. There are available makeup cosmetics of diverse types including solid foundations, liquid foundations, eye shadows, cheek colors, lip colors, eyeliners, mascara, sunscreen lotions, and the like, and in various forms including solid, non-aqueous, W/O emulsion, O/W emulsion, aqueous and the like.
From the aspects of feeling on use and daily UV protection, makeup cosmetic compositions are desired to have lasting quality. Particularly in summer or hot humid conditions and sports, they are desired to have water resistance, oil resistance and persistence. Coatings of makeup cosmetic compositions tend to undergo wrinkling and blotting due to sweat, sebum or the like, deteriorations such as peeling by contact, and cosmetic transfer such as staining to cups and cigarettes. One countermeasure taken in the art is by formulating synthetic resin emulsions or silicone resins having a film-forming ability in cosmetic compositions.
In general, coatings of synthetic resin emulsions are less water resistant in that they are susceptible to breakage or separation when wetted with water. Thus they are not satisfactory in lasting quality of cosmetics. For example, acrylic resin emulsions are often used in cosmetic compositions, but there is a likelihood of cosmetic spoiling due to short adhesion caused by the toughness of film. There is a demand for an emulsion for cosmetic use having higher water resistance and lasting quality.
One class of silicone resin commonly used includes triorganosiloxysilicic acids such as trimethylsiloxysilicic acid. For example, JP-A H09-143029 and JP-A H09-175940 disclose that a solution of trimethylsiloxysilicic acid in cyclic silicone is formulated in sunscreen lotions and cosmetic bases. It is known that formulating a silicone resin solution is effective for improving the feeling on use and lasting quality of cosmetics. However, when a silicone resin solution is applied in a model experiment and an actual use, the effect obtained on the actual use is not comparable to the effect obtained in the model experiment. This is because the cyclic silicone does not volatilize off, but remains on the skin and eventually prevents the silicone resin from exerting its effect.
JP-A H07-196449 discloses an eye makeup cosmetic composition comprising trimethylsiloxysilicic acid, a specific acrylic-silicone based graft copolymer, and a low-boiling silicone oil and/or low-boiling isoparaffin, which forms a uniform film with improved water resistance, sebum resistance, and lasting quality. Since the film is still insufficient in uniformity, water resistance, and sebum resistance, improvements in these properties are desired.
When trimethylsiloxysilicic acid is formulated in cosmetic compositions, the formulating technique involving dissolution in an organic solvent and subsequent emulsification is generally used in the prior art as alluded to in the cited patent documents. In the resulting mixture, trimethylsiloxysilicic acid is not uniformly admixed with the silicone component. For example, the method of JP-A H07-196449 can form a sea-island structure on the copolymer level, but there is still left a room for improvement in uniformity. This causes a film to become very hard, giving uncomfortable or stiff feel on the skin or heavy touch upon application. As the amount of trimethylsiloxysilicic acid blended is increased in order to prevent cosmetic spoiling, emulsification is retarded, making it difficult to obtain satisfactory storage stability. There exists a demand for a technique of uniformly formulating trimethylsiloxysilicic acid in cosmetic compositions.